This document summarizes research on nano-particles in heat transfer. It discusses how nanofluids are engineered by dispersing nanoparticles smaller than 100nm in conventional heat transfer fluids to enhance thermal performance. It outlines different types of nanoparticles and base fluids that can be used. The key mechanisms for how nanofluids improve heat transfer are liquid layering around nanoparticles, Brownian motion, and microconvection induced by nanoparticle movement. Experimental results show increases in thermal conductivity compared to base fluids alone. Parameters like particle size and material affect conductivity. Nanofluids have applications in solar energy collection and storage. Synthesis methods include two-step mixing of nanoparticles and base fluids or single-step production.

1. Nano-Particles in Heat Transfer
EN-317 Seminar
Satyaprajna Sarthak Sahoo 16D170026
Anshul Mahor 16D170025
Abhishek Sisodiya 16D170023
Manoj Vishwakarma 16D170022

2. Introduction
● Conventional Heat Transfer Fluids
○ Inherently have poor thermal performance.
○ Eg. Water, Ethylene Glycol, pumping oil etc.
● Nanofluids (NFs)
○ Nanofluids are a new class of advanced heat-transfer fluids
engineered by dispersing nanoparticles smaller than 100 nm in
diameter in conventional heat transfer fluids.
○ Thermal performance is enhanced.

3. Structure

4. Types of Nano-particle
Nanofluids
Nanoparticle
Carbon-basedAlloyPure MetallicCeramic
● Ag
● Cu
● Ni
● Au
● Fe
● Oxides
● Sulfides
● Carbides
● Cu-Zn
● Fe-Ni
● Ag-Cu
● Carbon nanotube
● Graphane
● Graphene oxide
● Graphite
Base Fluid Surfactants

5. Features of Nanofluids
● Higher heat conduction
○ The nanoparticles have a large surface area which allows more heat transfer.
○ Due to their tiny size, they are mobile and may bring about micro convection.
● Stability
○ The problem of sedimentation is resolved because the particles are small, they weigh
less, thus making the chances of sedimentation less.
● Reduced chances of erosion
○ Nanoparticles are very small hence the momentum they impart on a solid wall is very
small.
● Reduction in pumping power
○ In the case of nanofluids, the required increase in pumping power will be very moderate.

6. Mechanisms of Heat Transfer In
Nanofluids

7. Liquid-layering (static)
● It is assumed that the solid-like Nano layer acts as a thermal bridge
between a solid nanoparticle and a bulk liquid and so is key to
enhancing thermal conductivity.
● From this thermally bridging Nano layer idea, a structural model of
Nano fluids that consists of solid was suggested. Nanoparticles, bulk
liquid and solid-like Nano layers.
● Suggested model predicts up to eight-fold increase in thermal
conductivity of nanofluid, especially when the particle diameter is
Less than 10 nm.
● Maxwell model:

8. Particle aggregation (static)
● It has been indicated that when the nanoparticles are suspended in
the base fluid, on the effect of Van der Waals forces they are
agglomerated over time.
● There are no conclusive theories for the effect of aggregation on
thermal properties of nanofluids.
● When aggregation takes place at constant nanoparticle
concentration, the specific heat of nanofluid with suspended
nanoparticles did not change with respect to nanofluid with
aggregated nanoparticles, but its diffusivity and thermal conductivity
increase.

9. Brownian Particle diffusion (dynamic)
● Brownian motion of nanoparticles bring a contribution to thermal
conductivity by two ways:
○ directly via nanoparticle diffusion and
○ indirectly via intensification of micro-convection of fluid around
separate nanoparticles.
● The heat waves generated in nanofluids can resonate and change the
value of thermal conductivity.
● The direct contribution of Brownian motion to total heat transfer by
nanofluid diffusion is negligibly small.

10. Brownian motion-induced convection
● Micro-convection and mixing stimulated by nanoparticle oscillations
can affect significantly the macroscopic transport properties of
nanofluids
● This effect is additive to the thermal conductivity of a static dilute
suspension.
○ Keffective
=kstatic
+ kBrownian
● Since the speed of thermal wave propagation is much faster than the
particle Brownian motion, the static part cannot be neglected.
● The nonlinear thermal waves are the suggested reason for the high
thermal conductivity of nanofluids.

11. Thermal conductivity of nanoparticles and base fluids

12. Overview of Some Best Experimental Results

13. Effects of Some
Parameters on
Thermal
Conductivity of
Nanofluids
● Particle Volume Fraction
● Particle Size
● Particle shape
● Particle material
● Base fluid
● Temperature
● Effect of Acidity(pH)

14. Synthesis of Nanofluids
Nano particles can be produced from several processes such as-
● Gas condensation,
● Mechanical attrition or Chemical precipitation.
Two main techniques to produce Nanofluids:
● Two step method
● Single step method

15. Synthesis of Nanofluids
Two Step Method
Nanoparticles
Base Fluid
Direct
Mixing
Nanofluids
Dispersant
addition
Ultrasonification

16. Synthesis of Nanofluids
Single Step Method

17. Applications in heat transfer
Solar thermal collector
● The efficiency increases remarkably for low values of
volume fraction(<0.2%) of nanoparticles
Thermal Energy Storage
● Used as storage medium in solar thermal-energy
storage facilities
● High heat capacity and thermal conductivity
Solar cells
● To cool the solar cells
Solar Stills
● Adding nanotubes (CNTs) to the water inside a single
basin solar still
● Efficiency can be increased by 50%

18. Nanofluids in solar thermal collector

19. Nanofluids in solar stills
Common Solar Still Nanofluid in Solar Still

20. Indian Companies
using nanofluids
● Adnano Technologies
● Anderlab Technologies
● Tata Steel
● Auto Fibre Craft
● AVANSA
● Eris Technologies
● Mittal Enterprises
● Nilima Nanotechnologies
● Quantum Corporation (QCorp)
● Sisco Research Laboratories
● Vergenta India
● Velbionanotech
● Saivens Materials Inc.
● Redex Nano Labs

21. REFERENCES
[1]ENGINEERING NANOFLUIDS FOR HEAT TRANSFER APPLICATIONS (ROYAL INSTITUTE OF TECHNOLOGY (KTH)):
HTTPS://WWW.DIVA-PORTAL.ORG/SMASH/GET/DIVA2:712511/FULLTEXT01.PDF
[2]ASTUDY OF HEAT TRANSFER WITH NANOFLUIDS (SANJYOT VARADE*,CHINMAY PATIL AND S.P.WADKAR):
DEPARTMENT OF MECHANICAL ENGINEERING,SAVITRIBAI PHULE PUNE UNIVERSITY,PUNE,INDIA
HTTP://INPRESSCO.COM/WP-CONTENT/UPLOADS/2017/06/PAPER74314-318.PDF
[3]MECHANISMS OF ENHANCED HEAT TRANSFER IN NANOFLUIDS (J.A.EASTMAN):
HTTP://FNOES.INLN.CNRS.FR/FNOES-TALKS/EASTMAN.PDF
[4]NANOFLUIDS FOR HEAT TRANSFER:AN ENGINEERING APPROACH (ELENA VTIMOFEEVA*,WENHUA YU,DAVID MFRANCE,DILEEP SINGH,JULES LOUTBORT):
HTTP://IMAGES.BIOMEDSEARCH.COM/21711700/1556-276X-6-182.PDF?AWSACCESSKEYID=AKIAIBOKHYOLP4MBMRGQ&EXPIRES=1540771200&SIGNATURE=EF5W9U81WC6ZW
EBO0V6KM3JFFSQ%3D
[5]INVESTIGATION OF NANOPARTICLE AGGREGATION EFFECT ON THERMAL PROPERTIES OF NANOFLUID BY A COMBINED EQUILIBRIUM AND NON-EQUILIBRIUM MOLECULAR DYNAMICS SIMULATION
(MINA SEDIGHI,ALI MOHEBBI):
HTTPS://AC.ELS-CDN.COM/S0167732214001858/1-S2.0-S0167732214001858-MAIN.PDF?_TID=4047AFF8-561E-4110-8A35-CA537F349122&ACDNAT=1540674451_3BF65B2
DC468CBD15C0FA1D72B0EE3B9
[6]ASIMPLEYETEFFECTIVEMODELFORTHERMALCONDUCTIVITYOFNANOFLUIDS (M.M.MACDEVETTE,H.RIBERA,ANDT.G.MYERS):
HTTP://WWW.CRM.CAT/EN/PUBLICATIONS/PUBLICATIONS/2013/PR1149.PDF

22. THANK YOU